The invention relates to an auxiliary range transmission with two main countershafts and two auxiliary countershafts in a main and, respectively, an auxiliary transmission part.
U.S. Pat. No. 4,876,924 discloses an auxiliary range transmission, in which a main group and a range group are each provided with two independent countershafts. Three gearshift elements are provided in the main transmission. Two of these three gearshift elements are displaceable in both axial directions. The third gearshift element is displaceable in only one axial direction. Here the third gearshift element, in a merely schematic representation, is shown on the side facing the range group. In the detailed drawing associated with this schematic drawing, on the other hand, the third gearshift element is arranged on the side remote from the range group. Multiple spring-loaded clutches are further provided, which serve to couple loose gears of the range group to the associated main shaft.
U.S. Pat. No. 5,447,082 likewise discloses an auxiliary range transmission having a main group, a range group and parallel offset countershafts. The auxiliary range transmission here only has bilaterally acting gearshift elements. No gearshift element is provided between the loose gear of the main group and the loose gear of the range group
U.S. Pat. No. 6,257,082 B1 likewise discloses an auxiliary range transmission having a main group, a range group and parallel offset countershafts. In this case a gearshift clutch is provided between the main group and the range group.
The main object of the invention is to provide a cost-effective auxiliary range transmission, which, in spite of being compact in construction, has a large number of gears.